1. Field of the Invention
The present invention relates to a plasma-display panel and a method for manufacturing the same, and particularly relates to a surface discharge-type plasma display panel and a method of manufacturing therefor.
2. Background Art
A plasma display panel is a display device utilizing a gas discharge luminescence in inert gases such as neon or xenon. In the conventional plasma display panel, a two counter electrode discharge-type structure has been adopted, in which the image is displayed by selective discharge between intersecting portions of counter electrodes, one of which is a series of line electrodes formed on one panel plate, and the other of which is a series of row electrodes formed on the other panel plate. A typical structure of such a conventional two electrode type plasma display panel is shown in FIG. 12. In FIG. 12, a front plate 100 and a rear plates 102 using two glass plates are arranged so as to face each other. A plurality of line discharge electrodes 104 are formed on the front plate 100, and a plurality of row discharge electrodes 108 are formed on the back plate 102, in the direction that crosses the line discharge electrodes 104 at a right angle. A dielectric layer 106 is formed so as to cover the line discharge electrodes 104.
On the back plate 102, separating walls 110 are formed in the direction of the line discharge electrodes so as to partition the row discharge electrodes, and fluorescent material layers 112 are formed to cover the side surfaces of the separating walls as well as the row discharge electrodes 108. A discharge space 114 is filled with the discharge gas such as neon. In the above-described structure, a desired image is displayed by plasma luminescence by selective discharge of the line discharge electrodes 104 or the row discharge electrodes 108.
The above-described two-electrode-type plasma display panel has been used for monochromatic display. Recently, however, an essential requirement for the color display necessitates conversion of the ultraviolet light generated by the discharge into three visible light and formation of the three fluorescent material coatings in the discharge space. When such coatings are formed in the counter discharge-type panel, the fluorescent material films are likely to be bombarded by charged particles, so that degradation of the fluorescent materials results in short service life.
A new plasma display panel, proposed as a solution to the above-described problem, is a surface discharge-type plasma display panel, in which discharge takes place separated from the fluorescent materials, and the surface discharge-type has recently become the leading plasma display panel. In general, the surface discharge-type plasma display panel uses parallel electrode pairs comprising a scanning electrode and a sustain electrode and as well as a data electrode is disposed in the direction crossing the scanning and sustain electrodes at a right angle, so that this type of plasma display panel is called a three electrode surface discharge-type panel. The schematic structure of the three electrode surface discharge-type plasma display panel is illustrated in FIG. 13. As illustrated, this type of plasma display panels is constituted by a front insulating glass plate 60 disposed at the front side facing a back insulating glass plate 62 disposed at the back side, leaving a discharge space 80 therebetween.
On the front plate 60, the surface discharge electrode pairs comprising the scanning electrodes 72a and sustain electrodes 72b made of transparent films such as ITO or nesa films are formed. In addition, a trace electrode 74 made of metal is formed on the scanning and the sustain electrodes in order to reduce the resistance of those scanning and sustain electrodes. The trace electrode 74 is usually formed by a laminated thin film electrode made of Cr/Cu/Cr or the thick film electrode made of Ag.
Furthermore, these electrodes are covered by a dielectric layer 64. The dielectric layer 64 is usually formed using a low-melting glass. A protective film made of MgO (not shown) is formed on the dielectric film 64 in order to prevent the damage due to ions or plasma generated by the discharge and to reduce the discharge voltage as well.
On the back plate 62, the scanning electrode 72a and a data electrode 72b, made by a thick film of Ag are formed in the direction perpendicular to the sustain electrode 72b. Subsequently, on the data electrodes, a white dielectric film 68 is formed by printing and firing a glass paste made by mixing white oxide materials (alumina or titanium oxide) and a low-melting glass powder on the data electrode 78. This white dielectric layer 68 is used for reflecting visible light from the fluorescent material in order to enhance the efficiency of the emission of visible light. Furthermore, on this white dielectric layer 68, three types of fluorescent materials 70 are separately coated by thick film technology for converting the ultraviolet light due to the gas discharge into three types of visible light, R (red), G (green) and B (blue).
The front plate 60 and the back plate 62 are disposed facing each other enclosing separating walls (not shown) formed by an insulating material in matrix or stripe forms for forming discharge cells 76, and a discharge gas, constituted by helium, neon, xenon or a mixture of these gases, is filed in the discharge space 80. The above separating walls are formed by the thick film technology using a mixture of the low-melting glass with alumina, magnesium oxide, titanium oxide etc.
Hereinafter, the discharge operation of a selected discharge cell 76 will be described with reference to FIG. 14. First, in the preliminary discharge period, a preliminary discharge pulse PP is applied to the scanning electrodes 72a over the entire display surface area for generating discharge between the scanning electrodes 72a and the sustain electrodes 72b. Subsequently, in the elimination period for eliminating wall charges generated on the scanning electrode 72a and the sustain electrode 72b, a pulse train PE1, PE2, and PE3 is applied to the scanning electrode 72a and the sustain electrode 72b, respectively. In the writing period, a writing pulse PW is applied so as to scan all scanning electrodes 72a in sequence. In synchronism with the writing pulse PW, a data pulse PD in accordance with the desired display data is applied to the data electrode 78 for causing discharge between the scanning electrode and the data electrode.
Next, in the sustain period, the charge generated in the writing period is maintained as the surface discharge by applying a voltage pulse PSUS to both sustain electrodes 72a and 72b for the display. The above preliminary period and the elimination period play a role to produce reliably the discharge between the scanning electrode 72a and the data electrodes 78 corresponding to the display data generated in the writing period succeeding the preliminary period and the elimination period. Accordingly, the strong surface discharge over the entire surface followed by the weak discharge allows eliminating the wall charge on the electrodes forming the discharge cells as well as leaving the space charge due to the ionized particles in the discharge cells.
In the writing period, the discharge caused between the scanning electrode 72a and the data electrodes 78 forms the positive wall charge on the scanning electrodes 72a and the negative wall charge on the data electrode 78. When these wall charges are present, since these wall charges overlap with the pulse PSUS applied to the scanning electrode 72a and the sustain electrode 72b, it becomes possible to generate and maintain the surface discharge in discharge cells corresponding to the display data because the applied voltage exceeds the surface discharge starting voltage.
As described above, the conventional AC memory-type color plasma display panel uses a discharge between the scanning electrode 72a and the data electrode 78 facing each other for writing the display data. However, although the scanning electrode 72a is covered by a good discharge resistant material such as magnesium oxide, the data electrode 78 is covered by the fluorescent material 70. Thus, the voltage at the time of the writing discharge is applied such that the potential of the scanning electrodes 72a becomes more negative than the potential of the data electrodes 78. The objective of such potential application is to prevent degradation of the brightness due to the surface damage of the fluorescent material by suppressing collision of heavy positive charged ions which are likely to cause deterioration of the fluorescent material due to sputtering. Another objective is to prevent the brightness degradation and the change of the discharge voltage by scattering and adhesion of the sputtered fluorescent material layer 70.
However, even if the above measures are taken, there is a possiblility that a weak discharge is caused in the preliminary discharge period, in the erasing period, and in the writing period, at the time when the potential of the data electrode 78 is lower than the potential of the scanning electrode, and degradation of the brightness or the change of the discharge voltage are caused because the electron bombardment also damages the fluorescent material. Therefore, the problem arises that the brightness of a continuously lighting portion deteriorates sooner than the other portion when a fixed letter is continuously displayed. The same problem is likely to be caused such that degradation of the brightness for the primary colors differs from each other, and an inhomogeneous spot in the luminescence brightness, or so-called burning, results. The other problem is that the service life of the plasma discharge panel is not sufficient.
Japanese Patent Application, First Publication No. Sho 57-15340 discloses an AC-type plasma display panel, in which a matrix type electrodes crossing at a right angle through a dielectric layer is provided and the discharge luminescence for the display is generated at these intersecting points. This plasma display panel is not practical because it has the problems in that it is difficult to obtain sufficient insulation between electrodes at the intersecting portions and that the discharge voltage increases if the thickness of the insulating layer between two electrodes increases for sufficient insulation.
Japanese Patent Application, First Publication No. 5-101781 discloses a plasma display panel, which, on one hand, displays by the discharge luminescence generated at intersecting points of stereoscopic electrodes provided on the separating walls on the back plate, and which, on the other hand, controls the discharge by providing a trigger electrode (the third electrode) formed on the front plate. A problem arises in this type of plasma display panel that, since the fluorescent material layer is formed on the trigger electrode on the front plate, the fluorescent material layer is likely to deteriorate because of the discharge between the trigger electrode and the other electrodes on the back plate.
Those conventional plasma display panels have the common problem that the fluorescent material layer is exposed to the plasma discharge and it has been difficult to suppress the deterioration of the fluorescent material layer, even though those panels have the structure similar to the present invention in that the matrix type electrodes crossing each other at a right angle are formed and that the electrodes are formed on the separating walls.
If a plasma display panel can be provided based the luminescence due to the surface discharge by two electrode-type driving circuit constitution, it would be advantageous in achieving a plasma display device provided with a long service life by a simple driving sequence.
It is therefore an objective of the present invention to provide an plasma display panel and a method of manufacturing the same which has a long service life by suppressing deterioration of the fluorescent material layer.
According to the first aspect of the present invention, the plasma display panel obtained by the assembling and airtight sealing of a first substrate provided with a plurality of surface discharge electrode pairs formed by use of a conductive material arranged so as to form a matrix with a second substrate provided with separating walls and fluorescent material layers disposed so as to conform with said plurality of surface discharge electrode pairs, wherein the electrodes of one side of each electrode pair in said plurality of surface discharge electrode pairs are connected to each line bus wire among a plurality of line bus wiring formed extending along the line direction on said first substrate, and the electrodes of the other side of each electrode pair in said plurality of surface discharge electrode pairs are connected to each row bus wire among a plurality of row bus wires disposed along the row direction on said second substrate formed extending along the row direction on said first transparent insulating substrate.
According to the second aspect, in the plasma display panel according to the first aspect, the separating wall comprises a wall portion at least extending along the row direction and each electrode on the other side among a plurality of surface discharge electrode pairs is connected individually with said row bus wire by means of a connecting means including a plurality of transfer electrodes formed in said separating wall.
According to the third aspect, in the plasma display panel according to the second aspect, the mutually opposing end sides of two surface discharge electrodes constituting each of said surface discharge electrode pairs are disposed leaving a space from said separating wall.
According to the fourth aspect, in the plasma display panel according to the second aspect, along a direction along either the line direction or the row direction of said first transparent insulating substrate, said surface discharge electrode pair is partitioned by a black mask formed so as to intervene between an upper portion of the separating wall and said first transparent insulating substrate.
According to the fifth aspect, in the plasma display panel according to the fourth aspect, the mutually opposing end sides of two surface discharge electrodes constituting each of said surface discharge electrode pairs are disposed leaving a space from said black mask.
According to the sixth aspect, in the plasma display panel according to the third aspect, said space between the mutually opposing end sides of two surface discharge electrodes constituting each of said surface discharge electrode pairs is within a range of 20 to 150 xcexcm.
According to the seventh aspect, in the plasma display panel according to the second aspect, separating walls are formed in the form of stripes on said second insulating substrate, and fluorescent material layers are formed on the area of said second insulating substrate between said separating walls in the form of stripes including side surfaces of said separating walls.
According to the eighth aspect, in the plasma display panel according to the second aspect, said connecting means comprises a connecting electrode formed on said first transparent insulating film and a transfer electrode formed on said second insulating substrate, wherein said surface discharge electrode of one side of said surface discharge electrode pair is connected to said connecting electrode and said connecting electrode is electrically connected to said transfer electrode.
According to the ninth aspect, in the plasma display panel according to the second aspect, a pad electrode pattern is formed on each transfer electrode or on the connecting electrode, and wherein said pad electrode layer is composed of a material which can be melted and deformed simultaneously during the airtight sealing process of said first transparent insulating substrate and said second insulating substrate.
According to the tenth aspect, in the plasma display panel according to the eighth aspect, said connecting electrode and said transfer electrode are coupled by capacitive coupling intervening a dielectric layer.
According to the eleventh aspect, in the plasma display panel according to the tenth aspect, said dielectric layer has a capacity 100 times larger than that of the space between the one and the other electrodes of said surface discharge electrode pair.
According to the twelfth aspect, the method for manufacturing a plasma display panel at least comprises the steps of forming a plurality of surface discharge electrode pairs by a transparent conductive material so as to form a matrix on the first transparent insulating substrate; forming separating walls on the second insulating substrate; and forming fluorescent layers on the side walls and the bottom portions of said separating walls; wherein said step of forming separating walls comprises the steps of: forming the row bus wiring on the locations where the separating wall is formed; and forming in said separating walls transfer electrodes connected to said row bus wiring.
According to the thirteenth aspect, the method for manufacturing a plasma display panel at least comprises the steps of: forming a plurality of surface discharge electrode pairs made of a transparent conductive material so as to form a matrix on the first transparent insulating substrate; forming separating walls on the second insulating substrate; and forming fluorescent material layers on the side surfaces and bottom portions of said separating walls; wherein said pad electrode layer pattern formed on said second insulating substrate is connected with said connecting electrodes on said first transparent insulating substrate by softening and melting said pad electrode layer pattern during airtight sealing by use of a low-melting glass at the periphery of the assembled first transparent insulating substrate and the second insulating substrate while facing each other enclosing the separating walls.
According to the fourteenth aspect, in the method for manufacturing a plasma display panel according to the twelfth aspect, the method comprising: a first step of attaching a separating wall paste to the side surface of recessions of a photosensitive resin form, formed by patterning the photosensitive resin in a similar configuration to the desired separating wall pattern on said row bus wiring, by forcing the separating wall paste into the above recessions; a second step of filling the electrode paste in predetermined locations in the recessions of the photosensitive resin for forming the transfer electrodes after drying the separating wall paste adhering to the side surface of the recessions of the photosensitive resin form formed by said first step; and a third step of filling the separating wall paste in the recessions of the photosensitive resin form using a selective pattern so as to prevent adhering to said transfer electrode surface.
According to the fifteenth aspect, in said first step of the method for manufacturing a plasma display panel according to the fourteenth aspect, the separating wall paste selectively attached to the side surface of the recessions of the photosensitive resin form by filling up the separating wall paste having a viscosity of 500 to 1500 centipoise in the recession of the photosensitive resin form.
According to the sixteenth aspect, in the third step of the method for manufacturing a plasma display panel according to the fourteenth aspect, the separating wall paste is filled in the recessions of the photosensitive resin form by the use of a screen, which comprises intermittently formed rectangular patterns formed in one direction along said second insulating film so as to prevent adhering of the separating wall paste to the upper surface of the transfer electrodes.
According to the seventeenth aspect, the method for manufacturing a plasma display panel according to the fourteenth aspect further comprises the fourth step for forming pad electrodes on the transfer electrodes after completion of the third step by printing the electrode paste using a screen provided with a dotted pattern for forming pad electrodes.
According to the eighteenth aspect, the method for manufacturing a plasma display panel according to the fourteenth aspect further comprising the fifth step for forming pad electrodes on the transfer electrodes after completion of the third step by printing the electrode paste into a dotted pattern using a dispenser.
According to the nineteenth aspect, in the method for manufacturing a plasma display panel according to the seventeenth aspect, the paste for forming said transfer electrodes and the paste for forming the pad electrodes are metallic pastes, and the softening temperature of the paste for forming said transfer electrode is lower than that of the paste for forming said pad electrode.
According to the twentieth aspect, in the method for manufacturing a plasma display panel according to claim 13, said pad electrodes and said connecting electrodes are connected by the use of an electrode paste, the softening temperature of which is approximately 50xc2x0 C. lower than the softening temperature of the low-melting glass paste used at the time for carrying out airtight sealing of the periphery of the assembly in which said first transparent insulating substrate faces said second insulating substrate, with said separating walls interposed therebetween.
The plasma display panel according to the present invention displays a desired luminescent pattern, while scanning the surface discharge electrode on one side of the surface discharge electrode pairs, by use of the wall charge accumulated on the surface discharge electrodes on the other side of the surface discharge electrode pairs by applying a voltage corresponding to display data to said surface discharge electrodes.
The method of manufacturing the plasma display panel according to the present invention allows forming matrix in the horizontal and perpendicular directions by forming wiring for connecting to each electrode of the surface discharge electrode pairs on the other substrate.